Rotary table bushing



June ll, 1940. w. A. ABEGG ROTARY TABLE BUSHING Filed Feb. 7, 1959 3 Sheets-Sheet 1 June l1, 1940. w A. ABEGG ROTARY TABLE BUSHING Filed Feb. 7, 1939 3 Sheets-Sheet 2 .WW W hV n JM w M /W ok. @n

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June l1, 1940. w A, ABEG@ ROTARY TABLE BUSHING 5 Sheets-Sheet 5 .f2/fbg l lfarzfg Patented June 11, 1940 l UNITED STATES PATENT OFFICE ROTARY TABLE BUSHING Walter A. Abegg, Los Angeles, Calif., assignor of one-half to B. Reinhold, Los Angeles, Calif.

This invention has to do generally with bushings, and is more particularly concerned with bushings of a type commonly known as table or master bushings, used in rotary tables of Well drilling rigs.

The improvements represented by the present invention will be more readily understood by first briefly describing some of the ordinary functions of master bushings. The rotary, horizontally eXn tending table has a central bushing-receiving opening, commonly cylindrical in its lower part, square in its upper part, and with. an upwardly facing shoulder provided between the two par-ts. Within this table opening, is removably iitted a set of table bushings which, in turn, receive a set of pipe engaging bushings which may either be of the type commonly known as slips for supporting pipe, or of the type known as driving or kelly bushings used to engage a grief-pipe or kelly of polygonal cross section, the rotary drive being transmitted from the table through the table bushing, kelly bushing and kelly.

The table bushings, kelly bushings, andslips are each usually made in two or more sections. Due to the wedging action of the pipe supporting slips and the reactive forces involved in the driving torque whenl the kelly bushings are used, spreading pressure are put upon the table bushings, thus `tending to spread the table bushing' sections apart and developing loosenesses which ultimately result either in deformation of the pipe engaging members or putting uneven inward'radially directed pressure thereon in a manner which ultimately results in actually radially deforming and weakening the work. It has been found that most failures in drilling strings occur at points where the pipe engaging member or bushings take hold,` and it has been demonstrated that the reason for such localized failure is due to the uneven strains placed upon the work by reason of' the situation outlined above. f

I have devised a bushing which has the highly advantageous characteristic of being' movable bodily as a unit into and out of the table bore, the bushing being in the nature of p hingedly connected sections which may be swung open at one side for application to or removal from the work when the' bushing is clear of the table bore, and

yet have provided means whereby `the bushing fitting tightly within the table bore, it resulting that suicient clearance exists between table and bushing to allow free, rapid insertion or removal yet the free working clearance thus provided does f not permit the bushing sections from opening up -or loosening.

Generally, I accomplish the desired end by the use of'- a latch connection between the ends of the bushing segments or sections, this latch having a constant tendency to draw the free ends of said segments togethe-r and thus to hold the bushing in tightly constricted condition. Severaldifferent methods of insuring this tightly latched engagement are illustrated in the accompanying drawings, but the features of the particular mechanisms for accomplishingl the desired ends may be pointed out to better advantage as the following detailed description progresses. However, it is common to all the forms, that the outer face of the hook end of the latch is disposed in direct opposition to the defining wall of the table bore and thuspositively limited in its unlatching movement as long as the bushing is seated in the table bore.

Since the preferred type of latch is mounted for rotation about a Vertical axis, I have found it feasible to so fashion the latch body that centrifugal force has a tendency to constantly urge the latch in a direction to tightly constrict the bushing sections, this feature of utilizing'centrifugal force for the stated purpose being particularly appropriate to present day practices of rotating tables at relatively high speeds.

Other features of novelty and objects of th invention will be made apparent from the follow- I ing detailed description, reference being had to the accompanyingy drawings, in which:

Fig.'1 is a plan view showing my improved bushing as it appears when applied to a rotary table, and with drive or kelly bushings installed in the bore of the table bushing;

Fig. 2 is a vertical section taken on line 2-2 of Fig. 1;

Fig. 3 is a detached plan view of the table bushing, showing it unlatched and swung to open position from about the work;

Fig. 4 is an enlarged, fragmentary section on line 4 4 of Fig. l, but showing cylindrical work `substituted for the polygonal kelly bushing, and the substitution of slips for the. kelly bushing;

Fig- 5 is an enlarged, fragmentary plan section on line 5-5 of Fig. 4;

Fig. 6 is a section on line 6--6 of Fig. 5showing only the latch;

Fig. 'Z is a detached side elevation of the latch, as viewed from the right of Fig. 6;

Fig. 8 is a view similar to Fig. 5 but showing a variational type of latch;

Fig. 9 is a View similar to Fig. 5 but showing another variational type of latch;

Fig. 10 is a View like Fig. 5 but showing still another variational type of latch;

Fig. llis an enlarged fragmentary detail of the latch tightening means shown in Fig. 1U; and

Fig. 12 is a reduced section on line 2--l2 of Fig. 11.

A typical rotary table, mounted on bearings i@ and driven by geai` l l, is indicated at T, the table having a central opening or bore 9 whose lower part l2 is cylindric and whose upper part i3 is substantially square, the corners of the square preferably being relieved as shown in Fig. The cylindric defining wall of borepart i2 is indicated at i2. The square, upper part i3 of the table opening is suiiiciently large to present an upwardly facing shoulder M between parts l2 and E3. This shoulder may or may not be continuous around the opening, but is of suf cient extent to aiTord support for the master or table bushing generally indicated at M.

Table bushing M is made up of a plurality of segments or sections adapted to be hingedly con'- nected by a pin P at one set of their adjacent ends, while the opposite or distal ends are adapted to be disconnectedly joined by a latch generally indicated at L. In the specihc ferm here being described, the sections are in the form of halves H and H which, except for their hinge and latch formations, are substantially symmetrical.. When the sections are latched together the bushing may be bodily inserted in or removed from the table bore 9.

Each bushing section has a lower portion iii, the exterior surface of which is substantially cylindric, as indicated at it, which, when the two halves are latched together, form a substantially cylindric lower bushing assembly il adapted to fit freely and with slight annular clearance into the lower cylindric portion l2 of the table opening.

The upper portion of each bushing half or section is provided with a halfsquare :dange i8 which presents a downwardly facing shoulder i8 adapted to seat on the upwardly facing shoulder I4 of the table, the composite square or head made up of these two half-anges fitting fairly closely, but yet freely, into the square opening l 3 of the table and coacting with the defining wall of that square opening, there thus being provided drive shoulders whereby rotary motion of the tab-le is transmitted to the master bushing and, in turn, to work-engaging members (tobe described) carried by the bushing and thence to the work. On ,the other hand, shoulder it takes the bushing shoulder ld in a manner to support the bushing against downwardly directed loads which may be transmitted to that bushing from the work through work-engaging members, to be described.

The plane of separation of the two bushing halves, indicated by S in Fig. 3, and coinciding generally with the section line 4 4 of Fig. l, is here shown as on a diagonal of the square.

Near the joining ends of the two bushing halves, they are connected by pin P. As shown particularly in Fig. 4, the two bushing halves have intertting projections or hinge lugs bored for the reception of pin P which fits all the lugs relatively tightly but gives them a capacity for relative pivotal movement. The lugs on bushinghalf l-i are indicated at 2 i, while the lugs carried by bushing-half H are indicated at Z2.

Radially outward beyond the pin connection, the two bushing halves are relieved as at 23, so when latch L is released the bushing may be opened up as indicated in Fig. 3, the shoulders 2Q limiting the extent of spread.

Bushing halve H is provided at its distal end with vertically spaced latch lugs 25 and 26, the upper lug 25 preferably being of the same thickness as ange i3 and its upper face being substantially flush with the upper face of the bushing, proper. Lugs 2li and 2li carry a vertical pin 2l upon which latch L is mounted for pivotal inovement with relation to bushing half l-i. Latch L is U-shaped and consists of a body 23 having lugs 3B which interiit with bushing lugs Z5 and 2S, the hook end 3| of the latch extending vertically from a point just below iiange it to the lower end of the bushing. The latch hoolr is indicated at 32, the eifective latching shoulder 33 thereof extending from the top to bottom of the latch, shoulder 33 being related to the pivotal axis of the latch and preferably being so inclined (as illustrated in Fig. 5) as to effect a bushingclosing, camming action upon the keeper shoulder M of bushing half H', when the latch is rotated in a counterclocliwise direction, as viewed in Fig. 5. Shoulder 3ft is formed by one of the defining Walls of recess 36in bushing section H', shoulders 33 and 3E preferably being vertically co-extensive. The outer face 3l of hook end 3i is arcuate, being of substantially the same curvature as that of cylindric face lli and, when the latch is in closed position, being substantially flush with that cylindric face. Accordingly, when the latched bushing is lowered within the table bore, face 31 is opposed by defining wall l2 of the table bore I2, it following that the latch cannot possibly be moved to a release position so long as the bushing occupies the table bore.

Additionally, I provide means carried by the latch and coacting with bore wall I2 for constantly urging the latch in a bushing-closing direction, thus serving to forcibly hold the distal ends of the bushing halves against separative movement, to the advantageous ends spoken of in the forepart of the specification. This means comprises a bowed, leaf spring 38 which is taken in recess 33, sunk below the face 31 of hook end 3l, as clearly shown in Figs. 5, 6 and '7. One end of the spring is anchored as by bolt 4G, while the other end of the spring is slotted as at 4| to accommodate bolt 42, whereby that end of the spring is held from separative movement with respect to the latch, but is allowed to slide endwise during flexure of the spring. The spring is of such shape and tension that, in its engagement with bore wall l2', it exerts considerable radially directed force against latch end 3l in a manner tending to rotate that end in a counter-clockwise direction., as viewed in: Fig. 5, and

vthus constantly maintaining a tight bushingclosing effect.

It will be noted, however, that due to the shape and arrangement of spring 38, in spite of the fact that it will project radially outward beyond the projected bore of the table when the bushing centered with they table-bore but is vertically clear thereof, the spring will flex inwardly as the bushing is lowered into the table boreso as not to interfere with the easy insertion of the bushing within the table bore.

It will be noted that the distal end of bushing half Hf is vertically recessed as at 43 to accommodate, with clearance, the inner portions of latch` lugs 30 when the bushing is closed.

As a feature further tending to maintain the latch in a condition constantly urging the distal ends of the bushing halves into positions of tight closure, I preferably provide the latch with a relatively heavy tail 44 which, due to centrifugal action, tends always to swing the latch in a counter-clockwise direction, as viewed in Fig. 5, when the table, and hence the bushing, are rotated. Thus, as the angular velocity of the table is increased and therefore has an inn creased tendency to spread the bushing ends apart, that increased angular velocity has a greater tendency to throw the latch more tightly into bushing-closing position, thus counteracting the spreading eiect as imposed upon the bushing parts themselves.

Bushing half H is recessed at 45 to take weighted tail 44, the tail face 46, which may be considered as an extension of face 31, being shaped so that there will always be clearance between it and bore wall l2 so the centrifugal effect may not be lost by reason of tail-contact with that bore wall. Onv the other hand, the opposite face 41 is sufliciently spaced from recess wall 48 to allow the latch to be swung in a clockwise direction, as viewed in Fig. 5,- to unlatch the bushing when the bushing, as a whole, is clear of the table.

The upper or square portions of the bushing halves are recesed, as at 50, and the lower portions are internally cored out as at 5I to lighten the structure, ribs 52, however, giving the structure requisite strength. In the upper faces of the bushing sections I provide usual hook holes 53 to facilitate raising or lowering of the bushing. l

Though this is not limitative on the invention,

the internal opening in table bushing M may be of the form shown, wherein an upper, square portion 54 and lower tapered conical portion 55 provide an shoulder 56.

Bushings for -rotationally driving the work, such as rotary pipe or kelly K, may be of any suitable type, here being shown as a two-part kelly bushing 51 (although one-piece drive bushings are sometimes used) each bushing part 51a having a tapered lower portion 58 adapted to be takenA in the conical bore 55 of bushing M, and an upper rectangular portion 59 adapted to be taken in the square portion 54 of the table bushing. 'The composite internal opening 50 in the kelly bushing assembly, is shaped to conform intermediate, upwardly facing 'with the kelly in use, here being shown as square.

The reactive forces existing by reason of the driving .torque applied by bushing 51 tend to radially spread bushing parts 51a, and' either `that tendency or 'the spreading tendency accoinpanying the transmission of driving torque from the table bushing to bushing 51 tend to spread the halves of table bushing M. Or, if the kelly bushing be of one part, that onepart bushing still tends to spread the table bushing by reason of the torque forces. It has been explained above that spreading of the table bushing has very vharmful effect, but it will be seen that due to the provisions above described for counteracting this spreading effect and actually always tending to force the bushing parts more tightly together, this source of trouble is eliminated or at least reduced to a negligible factor, and therefore make of the bushing an appliance which in no l12 seated in recess 14, it tends to throw the latch way tends to weaken the work by'putting uneven strains and pressures thereon.

Likewise, by preventing the table bushing from spreading, the bushing is prevented from transmitting its spreading force to the table, thus preventing undue'wear upon the bore-defining walls of the table. l

It will be understod that in usual kelly bushings, the underface 6| rests upon the shoulder 56 o the table bushing, while the conical portion 58 of the kelly bushing is taken somewhat loosely in the conical bore 55 of the master bushing.

In 1Fig. 4, the work is shown in the form of a cylindric pipe or drill stem R, and usual pipe I supporting bushings or segmental wedge slips 1'155 64 are substituted for the kelly bushing 51. Slips 64 fit into the lower, conical portion 55 of the table bushing and, in riding down the tapered surfaces of that bore, wedgingly grip work R to prevent the latter from dropping. It will be '120 obvious that the lateral or horizontal forces involved in thisl wedge-gripping action are considerable and in some cases are extremely large. Obviously, these forces tend to spread the table bushing which spread, if not prevented, has the v512:5 harmful effects spoken of above. However, by the use of the latching means I have described,

lio

such spreading forces are counteracted and, in

effect, overcome.

In Fig. 8 I have shown a variational type of latch. All other parts of the structure may be similar to the corresponding parts of Figs. l to 5, inclusive, and therefore will be given the same reference numerals, obviating the need for repetitive description. l35

Here, the latch LI is mounted in the same manner as latch L and its hook end 3l has substantially the same characteristics as and functions in the same manner as latch end 3| except that the spring 38 is omitted. In place of this iff() spring, I provide means `for forcing the latch inwardly to hold the bushing parts tightly together, by the imposition of yieldable spreading means between wall 48 of recess 45 and the tail 44 of the latch. Thismeans comprises a compression spring 1i! about a bolt 1i which is mounted for relative endwise movement through tail 44. Spring 10 acts between bolt head 12 and tail shoulder 13 in such a manner, that, with head "50 in a counter-clockwise direction and thus more tightly constrict the master bushing segments.

Latch face 31 is opposed to bore-wall l2 in the manner previously described in connection with latch L, and is thus prevented positively Q55 from disengagement from bushing half H so long as the bushing is within the table bore. The tail is shaped so that it clears wall I2 suiciently to prevent engagement which would positively limit counter-clockwise movement of the latch, 6b and thus does not interfere with the functioning Ao1" hook end 3|', which is the same as that described in connection with end 3 1. Likewise, clearance exists between bolty head 15 and tail ,1 shoulder 16 so such counter-clockwise movement 65 of the latch is not prevented at this point.

However, when the bushing is bodily lifted from the table bore, tail 44 may be manually pressed in a clockwise direction against the tension of spring 1E) and hook end 3| thus cleared 'F70 from bushing half H to allow spreading of the bushing.` Upon subsequent closing of the bushing preliminarily to introduction in the table bore, latch L' will automatically be cammed outwardly by the engagement of kcam faces 18 and "15 ,18, on bushing part H` and the nose of latch L', respectively, and spring 18 will then act automatic-ally to swing the latch into operative or latching position.

Preferably, latch tail 44 is of suicient mass and is so positioned as to tend to rotate latch Ll more tightly into latching position and thus more tightly constrict the bushing about the work, under the influence of centrifugal force as set up by table-rotation.

In Fig. 9 I have shown a variational type of latch generally similar to latch Ll except for the latch-tightening means provided between the latch tail and bushing-segment H. In all other respects the structure and functions may be considered as equivalent to the previously described showings.

Here, the latch-tightening means is in the form of a wedge cone or spreader 88 threadably connected at 8| to bushing segment H and extended between the taper face 82 of that bushing segn ment and the taper face 83 on the free end of tail 44 of latch L2. Spreader 88 is thus positioned, in effect, within recess 45, while its outer end is exposed to recess 84 and is provided with a polygonal end-socket 85 to take an adjusting tool.

When the bushing is removed from the table bore, spreader 88 may be threadably adjusted by a tool introduced through recess 84 and. into socket 85, either projecting it further between faces 82 and 83 to tighten the latch (with the advantageous results spoken of above) or to retract cone from between faces 82 and 83 to allow clockwise movement of the latch to a position of clearance for permitting the bushing to be opened up.

Here again, the face 3l' of the latch is prevented by bore wall l2 from moving to open position in the event of failure of the spreading cone 8l), and tail 44" is of suflicient mass to give the latch self-closing effect under the iniluence of centrifugal force generated by table rotation.

In Figs. 10, ll and l2, I have shown a variational type of latch-tightening means. Except for this change, the bushing and latch parts are similar to and function as corresponding parts previously described. Here, the latch-tightening means applied to latch L3 is in the form of a bolt member 86 extending transversely of tail 44' and having threaded connection therewith at 8l. Bore 88, which accommodates bolt 86, opens to conical counterbore 89 which presents its large opening to the exterior of the latch tail. An. operating lever 98 has its upper forked end 9i pivotally connected at 92 to the end of bolt 8E, fork 9| lying within counterbore 88. The shank .92 of the lever normally hangs vertically within slot 93 of the bushing which extends downwardly from counterbore 89, the outer faces of the fork and lever being positioned so they do not extend outwardly beyond the outer face of the latch tail or of the bushing.

The inner end of bolt 88 is provided with a substantially spherical head 9d engaging com-- plementary, seat centrally provided in the conical spring washer G6 which engages at its base edge 9'! the square-cut shoulder 98 of bushing segment I-I, said shoulder 98 partially deiinu ing recess 45. The washer is held in assembly with bolt 85 by a nut 99 threaded on the tip or extension IDE! of the bolt, said extension passing through a central aperture in the washer. When the assembly is in condition of Fig. l0, it will be seen that` spring 88 is tensioned and thus exerts an outward radial thrust on bolt 86 and therefore tail 44' tending to rotate the latch in a direction to draw the bushing parts closely together. The bolt is rotated, when the bushing is clear of the table, to apply or release the latch or to vary the effective tension of spring 88 by lifting the lower end of operating lever 9E! approximately to the dotted line position of Fig. l2 and then swinging the handle through the arc permitted by the formation of conical counterbore 89. The engagement of the end of bolt tip H38 with body shoulder lill will limit the extent to which the bolt may be tightened so as never to put an undue strain upon washer 88.

With handle lying within recess 33 when the bushing is within the table bore, it will be seen that that handle prevents rotation of bolt 88 and thus holds the bolt in its adjusted posl tion, with spring washer 98 constantly urging the latch in a bushing-closing direction.

As in the previously described cases, tail 44', particularly in view of the appurtenances carried thereby, is of sufficient mass to give the latch self-closing or tightening effect under the in,

fluence of centrifugal force generated by table rotation.

When the bushing is removed from the table bore, bolt 86 is retracted suciently to relieve all tension on washer Sii and to move it bodily a sufficient distance toy permit inward swinging of the latch tail a distance suiiicient to clear the latch hook from bushing segment H.

In order to limit counter-clockwise movement of the latch when the bushing is opened up, I

provide .a stop lug H83 on the latch tail adapted to engage the inner wall its of recess 45 under this condition, though the stop is sufficiently spaced from face Hifi when the latch is applied to bushing segment I-l, to eliminate the possibility of that stop engaging face fllt in a manner to prevent the latch from swinging sufciently in a counter-clockwise direction to effect the tight constriction of the bushing-parts.

As in the other cases, the latch tail is preferably of a mass which will allow advantage to be taken of centrifugal force,.as has been described above.

While I have described preferred embodiments of my invention, it will be understood that various changes in design, structures, and arrangement may be made without departing from the spirit and scope of the appended claims.

I claim:

l. A bushing for insertion in the bore of a rotary table, comprising a plurality of complementary bushing sections forming, when closed together, a unitary bushing adapted eXteriorly to nt a table bore and interiorly to take pipe engaging members or other work, a hinge connection A between one set of adjacent section ends, a releasable latch pivotally mounted on one section and engageable with the adjacent section to hold the bushing closed, said latch being adapted to bepositioned within the tab-le bore and to be radially spaced from the defining wall of said bore when the bushing is inserted in said bore, so as not to interfere with the lowering or raising of the bushing into or out of the table bore cam surfaces on the latch and said adjacent section, and means acting while the bushing is closed to cause coaction between said cam surfaces in a manner tending to more tightly close the bushing to prevent accidental release of the latch during operation of the table.

2,4 bushing for insertion in the bore of a rotary table, comprising a plurality of complementary bushing sections forming, when closed together', a unitary bushing adapted exteriorly to t a table bore and interiorly to take pipe engaging members or other work, the bushing having a substantially cylindrical part, there being arecess in the cylindrical part opening to the outer peripheral face thereof, a hinge connection between one set of adjacent section ends, and a releasable latch pivotally mounted on one section and located in said recess, said latch being adapted to be radially spaced iromilie defining wall of the table bore when the bushing is inserted in said bore, said latch being engageable with Athe adjacent section to hold the bushing closed, and,` when in holding engagement lying wholly within the recess so as not to interfere with the lowering or raising of the bushing into or out of the table bore.

3.` A bushing for insertion in the bore ci a rotary table, comprising a plurality of complementary bushing sections forming, when closed together, a unitary bushing adapted exteriorly to t a table bore and interiorly to take pipe engaging members or other work, a hinge connectionbetween one set of adjacent section ends, a releasable latch pivotally mounted on one section and engageable with the adjacent section to hold the bushing closed, said latch being adapted to be positioned within the table bore and to bev radially spaced from the defining wall of said bore when the bushing is inserted in said bore, so as not to interfere with the lowering or raising of the bushing into or out of the table bore and means acting between the latch and said one section while the bushing` is closed to urge said latch pivotally in a manner tending to more tightly close the bushing. v i

4. In combination with a rotary table having a vertically extending, bushing-taking bore, a bushing for the bore and comprising a plurality of complementary bushing sections forming, when closed together, a unitary bushing adapted exteriorly to iit the table bere and interiorly to takepipe-engaging members or other work, said bushing being vertically movable as a unit into and out of seated position within said bore, a hinge connection between one set of adjacent section ends, a latch pivotally movable about a vertical axis and mounted near one end of a second set of adjacent section ends .and movable, when the bushing is unseated, to and from a position engaging the other end of said second set to hold the bushing closed, said latch being positioned within the table bore and being radially spaced from the defining wall oi?` said bore when the bushing is seated in said bore, so as not to interfere with the lowering or raising of the bushing into or out of the table bore and a weight on said latch disposed in a position to cause said latch to have an effective tendency to move in ya bushing-holding direction under the inuence of centrifugal force when the table is f rotated.

5. In combination with a rotary table having a vertically extending, bushing-taking bore, a bushing for the bore and comprising .a plurality of complementary bushing sections forming, when closed together, a unitary bushing adapted exteriorly to t the table bore and interiorly to take pipe-engaging members or other work, said bushing being vertically movable as a unit into and out of seated position within said bore, a hinge connection between one set o-f adjacent section ends, a latch mounted for pivotal movementH about a vertical axis and carried by one of the sections, said latch being movable into and out oi a position of latching engagement with an adjacent section and acting when the bushing is within the table bore, to hold the bushing closed, a portion of said latch being movable outwardly with respect to the bushing axis when the latch is moved out oi-latching engagement, said portion being opposed to the defining wall of the table bore and radially spaced therefrom a distance less than the extent of latch movement necessary to disengage the latch from said adjacent section.

t. In combination with a rotary table having` a vertically extending, bushing-taking bore, a bushing for the bore and comprising a plurality of complementary bushing sections forming, when closed together, a unitary bushing adapted exteriorly to fit the table bore and interiorly to take pipe-engaging members or other work, said bushing being vertically movable as a unit into and out oi' seated position within said bore, a hinge connection between one set of adjacent section ends, a latch on one of the sections for movement into and out of a position of latching engagement with an adjacent section and acting when the bushing is within the table bore, to hold the bushing closed, a portion of said latch being movable outwardly with respect to the bushing axis when the latch is moved out of latching engagement, said portion being opposed to the defining wall of the table, and means acting between the bore defining Wall and said portion to urge said latch in a manner tending to more tightly close the bushing.

7. In combination with a rotary table having a vertically extending, bushing-taking bore, a bushing for the bore and comprising a plurality of complementary bushing ,sections forming, when closed together, a unitary bushing adapted ex. teriorly to t the table bore and interiorly to take pipe-engaging members or other work, said bushing being vertically movable as a unit into and out of seated position within said bore, a hinge connection between one set of adjacent section ends, a latch on one of the sections for movement into and out of a position of latching env gagement with an adjacent section and acting when the bushing is within the table bore, to hold the bushing closed, a portion of said latch being movable outwardly with respect to the bushing axis when the latch is moved out .of latching engagemena'said portion being opposed to the dening wall of the table, and a spring carried by the latch and acting between the bore dening Wall and said portion to urge said latch in a manner tending to more tightly close the bushing.

8. A bushing for insertion in the bore of a rotary table, comprising a plurality ofv complementary bushing sections forming, when closed together, a unitary bushing adapted exteriorly to lit a table bore and interiorly to take pipe engaging members or other work, a hinge connection between one set of adjacent section ends, av

releasable latch mounted for pivotal movement on one section and engageable with the adjacent section to hold the bushing closed, said latch being adapted to be positioned within the table bore and to be radially spaced from the deiining Wall of said bore when the bushing is inserted in said bore, so as not to interfere with` the lowering or raising of the bushing into or out oi the table bore and releasable holding means adapted to hold the latch yin a vpositionof engagement with the adjacent section.

9. A bushing for insertion in the bore of a rotary table, comprising a plurality of complementary bushing sections forming, when closed together, a unitary bushing adapted exteriorly to t a table bore and interiorly to take pipe engaging members or other Work, a hinge connection betweenone set of adjacent section ends, a releasable latch carried by one section and engageable with the adjacentsection to hold the bushing closed, said latch being adapted to be positioned Within the table bore and to be radially spaced from the defining Wall of said bore when the bushing is inserted in said bore, so as not to interfere with the lowering or raising of the bushing into or out of the table bore and releasable holding means adapted to hold the latch in a position of engagement with the adjacent section, said holding means being adjustable to Vary the tightness of latch engagement, and releasable means for maintaining the holding means in adjusted condition.

10. A bushing for insertion in the bore of a rotary table, comprising a plurality of complementary bushing members forming, when closed together, a unitary bushing adapted exteriorly to t a table bore and interiorly to take pipe engaging members or other work, a hinge connection between one set of adjacent member ends, ya releasable latch member carried by one bushing member and engageable with the adjacent bushing member to hold the bushing closed, said latch being adapted to be positioned within the table bore and to be radially spaced from the defining wall of said bore when the bushing is inserted in said bore, so as not to interfere with the lowering or raising of the bushing into or out of the table bore and an actuator threadably mounted in one of the members and engageable Y with another member to move the latch towards engaging position.

1l. In combination with a rotary table having a vertically extending, bushing-taking core, a bushing for the bore and comprising a plurality of `complementary bushing sections forming, when closed together, a unitary bushing adapted exteriorly to i'it the table bore and interior-ly to take pipe-engaging members or other work, said bushing being vertically movable as a unit into and out of seated position within said bore, a hinge connection between one set of adjacent section ends, a releasable latch pivotally mounted on one end of a second set of adjacent section ends .and pivotally movable, when the bushing is unseated, to and from a position engaging the other end of said second set to hold the bushing closed, said latch being positioned on the bushing to lie below the table top and being radially spaced from the defining Wall of the table bore when the bushing is seated.

l2. A bushing for insertion in the bore of a rotary table, comprising a plurality o1" complementary bushing sections forming, when closed' together, a unitary bushing adapted exteriorly to `t a table bore and interiorly'to take pipe engaging members or other word, the bushing having a substantially cylindrical part, there being a recess in the cylindrical part and opening to the outer peripheral wall thereof, a hinge connection between one set of adjacent section ends, and a releasable latch mounted for pivotal movement about a vertical axis o-n one section and located in said recess, said latch having hook and tail portions at opposite sides of the pivotal axis, the hook portion being engageable with the adjacent section to hold the bushing closed, and the latch being adapted, when the nook portion is in holding engagement and the bushing is seated within the table bore, to lie Wholly within the recess with the outer face of the hook portion, where it is exposed atthe outer side of the recess, extending substantially in flush relationship to the cylindric face of the bushing and the outer face of the tail portion extending somewhat below said cylindric face.

13, A bushing for insertion in the bore of a rotary table, comprising a plurality of complementary bushing members forming, when closed together, a unitary bushing adapted exteriorly to iit a table bore and interiorly to take pipe engaging members or other work, a hinge connection between one set of adjacent member ends, a releasable latch member carried by one bushing member and engageable with the adjacent bushing member to hold the bushing closed, said latch member being adapted to be positioned within the table bore and to be radially spaced from the dening wall of said bore when the bushing is inserted in said bore, so as not to interfere with the lowering or raising of the bushing into or out of the table bore, an actuator threaded in the latch member, and yieldable means connected to the actuator and engaging one of the bushing members to move the latch towards engaging position.

WALTER A. ABEGG.

CERTIFICATE 0E- CORRECTION. s Patent No. 2,20LL,112. rune 11, 191m.

wALT'ER A. ABEGG.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as' follows: Page 6, first column, line 1414, claim 11, for the word "core" read --bore; and second column, line l5, claim 12, for ."word" read 'work; and that the said' Letters Patenty should'be read with this correction therein that the same may conform to the record of the case in the Patent Office. I Signed and sealed thisl 6th day of August, A. D. 1911.0.

- Henry Van Arsdale, (Seal) Acting Commissioner of Patents. 

